1. Field of the Invention
The present invention relates to multi-image capture device capturing images by means of circular motion.
2. Description of Related Art
Displacement measurement is an important structural monitoring program, and also one of the parameters of safety assessment. The engineering sector has made effort in research and development of fast, convenient and effective measurement of deformation of structure.
Optical methods are always the potential displacement investigation way because optical methods can always perform non-contact measurement. A typical optical method consists of an optical signal source which will be the measurement point such as laser, LED, camera or other special optical devices; a reflective components which can be a mirror, prism, and other optical devices to reflect the light emitted from light sources; a light detecting or signal receiving devices which can be a photodiode, CCD, complementary metal oxide semi-conductor (CMOS) sensor all those who can convert light intensity into signal.
The displacement measurement systems which are implemented from optical methods need not to be contact with the measurement point, greatly reducing the limitation to the location for mounting the instrument and the labor and time needed for setup of the measurement systems. Moreover, it can be applied to remote displacement measurement with high freedom in use and therefore more acceptable by the engineering sector.
Thanks to the rapid development of camera technology in recent years, the image resolution is significantly improved to achieve high degree of accuracy. Image analysis technologies can be realized in reasonable time interval that make the photogrammetry becomes one of the powerful non-contact remote measurement methods. The basic concept of the digital photogrammetry is to locate a specific point of the measurement location in the image, compare the locations of the measurement points obtained at different times, and then calculate the displacement of the measurement points, by this way, it is easy to get good measurement result as long as the measuring points are clear in the image. mage analysis not only has the advantages of non-contact measurement method but also has small impact by the in-situ environment. Therefore, such a technical basis is put into the development of this invention for quick measurement of structural deformation.
In the application of 3D visualization, two images are taken at different locations with two CCD cameras. The relative depth of the whole scene can be re-constructed from two captured 2D images. The typical configuration which is used to set two cameras for non-contact image measurement of structural deformation is a straight bracket with image capture device to adjust the rotation and pitch angle of these two CCD cameras. FIG. 1 is a schematic view of a conventional image measurement structure.
An image measurement structure includes a straight bracket 41 and two image capture devices 42, realizing a physical architecture of a three-dimensional visual measurement. It is used to measure surface deformation of the whole object. Such a technology uses the characteristics of the object surface's images to determine the surface displacement. With combination with camera image capture and image comparison algorithm, the measurement of 3D surface deformation can be completed within the shorted time with best resolution. Any slight surface displacement can be presented in data and images so that the displacement and strain of a single point or the whole surface can be acknowledged.
In the above case, two image capture devices 42 are used for measurement. When the measurement range is out of the visual range of the image capture devices 42, limited images can be observed and the area masked by the object cannot be measured. Measurement of objects having different shapes needs to adjust the positions of the camera and also to perform calibration of the image capture devices for each object.
In summary, it has been long time for the image capture device to suffer limited visual range and need of frequent calibration. Therefore there is a need of a novel means to solve the above problems.